It's probably happened to you. You're in a hurry, you can't find your keys, so you put something down on the roof of the car. It might be your coffee, it might be your wallet, it might be your lunch. Whatever it is, you get in the car and forget to grab the object. And then drive away. You might notice it at the first turn, the first stop sign, or when you get home and can't find it.

Losing your coffee is annoying, but it could be worse. Here's a list of some of the strangest things that have fallen off of cars and trucks.

"Less Than Lethal" Grenade Launcher

An RCMP officer near Maple Ridge, BC, was alerted by a motorist that his truck cap was open. What had fallen out? A bag containing a grenade launcher. And ammunition. Fortunately, this was a "less than lethal" launcher, meaning it fired tear gas, smoke, and rubber bullets. Even more fortunately, it was returned to police a few weeks later.

Bride and Groom

Sometimes it's not an object, it's a person. Or people. Ask this newlywed couple that was sitting on the back of a Mercedes convertible. When the driver pulled away, the couple found out that a tux and dress don't offer much traction on the back of a car. Fortunately, the couple were okay.

(Part of) A Truckload of Cash

If you've ever left your wallet on the roof, you won't be surprised to hear that a lot of money falls out of cars or trucks. Just ask Dan Kennedy, a Salt Lake City man who tried to move a bag he found on I-80, near the Salt Lake city airport.

He went to drag the bag off of the road to discover that it was over 120 cm tall and nearly 60 cm wide. And it weighed nearly 40 kg. That's because it was a bag full of money, fallen from a Brink's truck. Kennedy returned the money but wasn't told exactly how much it was. An estimate based on the weight of the bag suggests it could have been well over a million.

Tomahawk Missile

This truck driver's loss could have been a real blast. A rear-ending ended with a Tomahawk missile on the highway. The 6 m long, 1,600 kg long range missile was in a protective case. The Air Force claimed that it was a practice round, not a real missile, but it still caused a big scare.

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Flying Bicycle

If you use a cargo box or bike rack, make sure that it's well secured. And make sure that whatever is in it is also secured. Ask this driver who was overtaken by a Range Rover that promptly dumped one of the two bikes on the rack onto the road.

Cargo Ship Engine

This might be one of the biggest objects to ever fall off of a truck. It's the engine for a US Navy cargo ship, the USNS Amelia Earhart. The 172 ton engine was being delivered to the shipyard but went to the wrong gate. The driver hit a curb backing up and the rest was up to gravity.

The engine completely flattened two cars and crushed the nose of a Ford Aerostar van. There was a woman sleeping in the back of the van who was unhurt but probably got the fright of her life. The engine left a hole 2.4 m deep in the road and ruptured a water main.

Also "Less-Than Lethal": Taser

Another dangerous drop by a police officer, who left a Taser on the roof of his car. The officer, from Brisbane, Australia, was shocked to realize he had left the electronic weapon on the roof of his patrol car. He returned to the scene to find the case, but it was empty. At the time, the police commissioner seemed less than worried about the loss, saying "from time to time we lose kit, it happens." Fortunately, the Taser was later recovered.

A Car... Off a Ferry

This time, a whole car was left on the roof. Well, a car was left unsecured on a ferry. And the ferry operators had left the gate down. This time it was near Fraser Island, again in Australia. The SUV was parked on the ferry but wasn't properly secured. It rolled off the back of the boat, right into the Pacific Ocean. The SUV floated for a minute or so but eventually sank.

Most of the Back of a Car

This one ends with a bang. The bang of an axle deciding it doesn't want to play anymore. Tearing the axle out of a car was made famous in American Graffiti, where a police car was chained up, causing the axle to separate. A few years ago, Mythbusters called it busted, saying an axle couldn't just fall out of a car that way.

Well cars, uh, find a way. Ask the driver of this vintage Dodge Dart. He was driving through Edmonton, enjoying some lovely V8 noises when the rear axle, differential, and wheels all decided that they didn't want to be any part of his car anymore.

Wallet... and Phone

I'll save my favourite for last. It's just one more reason why you should be polite to other motorists. This British motorcyclist is cut off by the driver of a Hyundai hatchback. The driver of the car has left his wallet and phone on the roof. The motorcyclist picks up the wallet and tries to give it back. The driver of the car replies by flipping the rider off. When the driver finally stops, the motorcyclist throws the driver's wallet into the car, and then slowly and deliberately taunts returning the phone before dropping it to the ground.